Long carry and excellent directional stability are required in golf clubs and their associated golf club heads. In order to satisfy these requirements, a high degree of design freedom regarding the center of gravity and moment of inertia is sought in the structure of the golf club head. In recent years, in order to raise the degree of design freedom of the center of gravity and moment of inertia, a composite type of golf club head has been proposed in which a metal member is placed in a low position and a fiber reinforced plastic member is placed in a high position (see, for example, Japanese Patent No. 2773009 and Japanese Laid Open Patent Publication Nos. 59-90578 and 2002-336389). These documents are entirely incorporated herein by reference.
The carry when a golf ball is hit by a golf club head depends to a large extent on the initial velocity of the ball. On the other hand, the initial velocity of the ball depends on the amount of kinetic energy transmitted to the ball from the golf club head. Accordingly, the carry distance typically can be lengthened by increasing the amount of kinetic energy that is transmitted to the ball.
Following on from this, in order to increase the amount of kinetic energy that is transmitted to a golf ball, golf club heads have been proposed that include special features in the structure of the club head's face plate. See, for example, U.S. Pat. Nos. 6,354,962; 6,368,234; and 6,398,666. These patents are entirely incorporated herein by reference.
However, in these known golf club heads, because a large amount of kinetic energy is expended in deforming the golf club head at the moment the ball is hit, it has not been possible to sufficiently increase the initial velocity of the ball so as to lengthen the carry.